Skiing and slalom courses for areas subject to snow in the winter are extremely popular and attract much attention. Likewise, bobsleigh runs can be constructed out of packed snow and provide much entertainment and enjoyment. In more temperate regions, however, where winter snow cannot be relied on, there are no corresponding winter entertainments and, even in those regions which enjoy snow in the winter there are no corresponding entertainments for the summer.
It is believed that one of the major reasons why snow-orientated winter sports are so popular lies in the excitement and freedom of a downhill slide, and in the fact that turning from a straight line path involves banking over into the turn. Although two-wheeled vehicles such as bicycles and motor cycles provide this physiological experience there are significant disadvantages to their adoption for a downhill run vehicle, largely due to the lack of directional stability on soft ground such as grassy slopes, and the fact that a smooth tarmac road on which a bicycle or motor cycle is most convenient and comfortable to use, detracts from the freedom and excitement of the open air cross-country experience of skiing or bobsleighing.